This invention relates to a control device for a vehicle and more particularly to an improved automatic speed control arrangement for a vehicle engine.
In many instances, it is desirable to provide for both manual and automatic speed control for an internal combustion engine. For example, if the engine is employed for driving a vehiclee and also driving a power takeoff shaft, there are times when it is desirable to permit the operator to control the speed of the engine and its output shaft at his will. At other times, however, it is desirable to insure automatic speed control so as to insure against variations in speed in the output shafts. For example, many accessories that are driven by a power takeoff shaft have a certain speed rating and it is essential to insure that that speed rating is not exceeded.
It is, therefore, a principal object of this invention to provide an improved arrangement for permitting either manual or automatic speed control of an engine.
It is a further object of this invention to provide an improved and simplified arrangement for permitting shifting between manual and automatic speed control.
In connection with the utilization of the automatic speed control, if the operator must make a separate adjustment to automatic speed control when the power takeoff shaft is being utilized, there is always the danger or possiblility that the operator may inadvertently neglect to shift into the automatic speed control mode.
It is, therefore, a still further object of this invention to provide an arrangement wherein automatic speed control is selected immediately upon the operator selecting the drive of the power takeoff without necessitating a further adjustment or manipulation by the operator.
Governor mechanisms of the type heretofore employed have generally been driven by the engine crankshaft. The crankshaft driven governor is mechanically coupled to a speed controlling element of the engine, normally the carburetor throttle valve, for controlling the speed automatically. However, when the governor is driven by the engine output shaft, it rotates at a much higher speed than the output shaft of the power takeoff. As a result, the governor is quite highly loaded and also must operate over a very wide speed range. Thus, governors of the type heretofore proposed have had to be relatively heavy and also extremely accurate.
It is, therefore, a further object of this invention to provide an automatic speed control mechanism wherein the governor is driven at a lower speed than with the prior art type of devices.
It is a yet further object of this invention to provide a governor mechanism that is driven from the power takeoff shaft and thus will control the actual speed of rotation of the shaft rather than engine speed.